Without limiting the scope of the present invention, its background will be described with reference to producing multiple hydrocarbon bearing subterranean zones in a well, as an example.
It is common to encounter hydrocarbon wells that traverse more than one separate subterranean hydrocarbon bearing zone. In such wells, the separate subterranean hydrocarbon bearing zones may have similar or different characteristics. For example, the separate subterranean hydrocarbon bearing zones may have significantly different formation pressures. Even with the different pressures regimes, it may nonetheless be desirable to complete each of the multiple zones prior to producing the well. In such cases, it may be desirable to isolate certain of the zones from other zones after completion.
For example, when multiple productive zones that have significantly different formation pressures are completed in a single well, hydrocarbons from a high pressure zone may migrate to a lower pressure zone during production. It has been found, however, that this migration of hydrocarbons from one zone to another may decrease the ultimate recovery from the well. One way to overcome this fluid loss from a high pressure zone into a lower pressure zone during production and to maximize the ultimate recovery from the well is to initially produce only the high pressure zone and delay production from the lower pressure zone. Once the formation pressure of the high pressure zone has decreased to that of the lower pressure zone, the two zones can be produced together without any loss of reserves. It has been found, however, that from an economic perspective, delaying production from the lower pressure zone while only producing from the high pressure zone may be undesirable.
A need has therefore arisen for an apparatus that provides for the isolation of separate zones traversed by a wellbore. A need has also arisen for such an apparatus that does not required delayed production from a lower pressure zone during production from a high pressure zone. Further, a need has arisen for such an apparatus that does not allow fluid loss from a high pressure zone into a lower pressure zone if both zones are produced at the same time.